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dhcp, ndp, dhcpv6: Support for multiple DNS servers, search list

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Add support for a variable amount of DNS servers, including zero,
from /etc/resolv.conf, in DHCP, NDP and DHCPv6 implementations.

Introduce support for domain search list for DHCP (RFC 3397),
NDP (RFC 8106), and DHCPv6 (RFC 3646), also sourced from
/etc/resolv.conf.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Stefano Brivio 2021-05-21 11:14:47 +02:00
parent 0231ac1c86
commit 9010054ea4
6 changed files with 312 additions and 45 deletions

77
passt.c
View file

@ -299,30 +299,49 @@ out:
*/
static void get_dns(struct ctx *c)
{
struct in6_addr *dns6 = &c->dns6[0];
struct fqdn *s = c->dns_search;
uint32_t *dns4 = &c->dns4[0];
char buf[BUFSIZ], *p, *end;
int dns4 = 0, dns6 = 0;
FILE *r;
r = fopen("/etc/resolv.conf", "r");
while (fgets(buf, BUFSIZ, r) && !(dns4 && dns6)) {
if (!strstr(buf, "nameserver "))
continue;
p = strrchr(buf, ' ');
end = strpbrk(buf, "%\n");
if (end)
*end = 0;
if (p && inet_pton(AF_INET, p + 1, &c->dns4))
dns4 = 1;
if (p && inet_pton(AF_INET6, p + 1, &c->dns6))
dns6 = 1;
while (fgets(buf, BUFSIZ, r)) {
if (strstr(buf, "nameserver ") == buf) {
p = strrchr(buf, ' ');
if (!p)
continue;
end = strpbrk(buf, "%\n");
if (end)
*end = 0;
if (dns4 - &c->dns4[0] < ARRAY_SIZE(c->dns4) &&
inet_pton(AF_INET, p + 1, dns4))
dns4++;
if (dns6 - &c->dns6[0] < ARRAY_SIZE(c->dns6) &&
inet_pton(AF_INET6, p + 1, dns6))
dns6++;
} else if (strstr(buf, "search ") == buf &&
s == c->dns_search) {
end = strpbrk(buf, "\n");
if (end)
*end = 0;
p = strtok(buf, " \t");
while ((p = strtok(NULL, " \t")) &&
s - c->dns_search < ARRAY_SIZE(c->dns_search)) {
strncpy(s->n, p, sizeof(c->dns_search[0]));
s++;
}
}
}
fclose(r);
if (dns4 || dns6)
return;
err("Couldn't get any nameserver address");
exit(EXIT_FAILURE);
if (dns4 == c->dns4 && dns6 == c->dns6)
warn("Couldn't get any nameserver address");
}
/**
@ -785,8 +804,17 @@ int main(int argc, char **argv)
inet_ntop(AF_INET, &c.mask4, buf4, sizeof(buf4)));
info(" router: %s",
inet_ntop(AF_INET, &c.gw4, buf4, sizeof(buf4)));
info(" DNS: %s",
inet_ntop(AF_INET, &c.dns4, buf4, sizeof(buf4)));
for (i = 0; c.dns4[i]; i++) {
if (!i)
info(" DNS:");
inet_ntop(AF_INET, &c.dns4[i], buf4, sizeof(buf4));
info(" %s", buf4);
}
for (i = 0; *c.dns_search[i].n; i++) {
if (!i)
info(" search:");
info(" %s", c.dns_search[i].n);
}
}
if (c.v6) {
info("NDP/DHCPv6:");
@ -794,8 +822,17 @@ int main(int argc, char **argv)
inet_ntop(AF_INET6, &c.addr6, buf6, sizeof(buf6)));
info(" router: %s",
inet_ntop(AF_INET6, &c.gw6, buf6, sizeof(buf6)));
info(" DNS: %s",
inet_ntop(AF_INET6, &c.dns6, buf6, sizeof(buf6)));
for (i = 0; !IN6_IS_ADDR_UNSPECIFIED(&c.dns6[i]); i++) {
if (!i)
info(" DNS:");
inet_ntop(AF_INET6, &c.dns6[i], buf6, sizeof(buf6));
info(" %s", buf6);
}
for (i = 0; *c.dns_search[i].n; i++) {
if (!i)
info(" search:");
info(" %s", c.dns_search[i].n);
}
}
listen: